Male cories are more streamlined. If you look at female cories from above the widest part of their body is just above their ventral fins but on a male their widest part is level with the pectoral spines. It's easier to determine in peppered cories though becuase they have sexual dimorphism. The female has a stornger pattern. This link shows a picture of two peppereds sitting together. The females will look fat even if they aren't pregnant.http://http://www.planetcatfish.com/...hp?f=6&t=23250

Male cories are more streamlined. If you look at female cories from above the widest part of their body is just above their ventral fins but on a male their widest part is level with the pectoral spines. It's easier to determine in peppered cories though becuase they have sexual dimorphism. The female has a stornger pattern. This link shows a picture of two peppereds sitting together. The females will look fat even if they aren't pregnant.http://http://www.planetcatfish.com/...hp?f=6&t=23250